Field of the Invention
This movement further comprises an adjusting device for causing this indicator to carry out supplemental adjusting steps, in order to automatically allow for months with 28, 29 or 30 days.
More particularly, and in advantageous fashion, this movement is designed to be able to easily adapt on a movement comprising a driving device of a conventional date display.
Moreover, the movement according to the invention makes it possible to display supplemental day, month and/or year information, without making major modifications to the movement.
There is already known from the Swiss patent CH 574 125 a control mechanism of a semiperpetual calendar, comprising a date ring whose single lever accomplishes the intermediate daily advance and the correction, at the end of certain months, by means of a mechanism. This correction is done by means of a mechanism comprising a month cam in connection with a device for locking the date ring. Such a mechanism has the disadvantage of being complex and costly to implement.
Furthermore, this mechanism is semiperpetual, that is, it does not take into account leap years and it requires the use of a day display and monthly correction mechanism.
Furthermore, there is known from patent EP 0 052 070 a perpetual driving device for the date ring, comprising a month cam and a year cam to perform the required correction of the display at the end of months with fewer than 31 days. This design is complicated and cannot be adapted to a movement comprising a traditional date display device. Furthermore, this system does not allow the display of information supplemental to the date display, such as the day, months, and the leap year.
The Swiss patent CH 169 64 describes a mechanism which does not take account of leap years and which comprises a system of small-dimension, variable-notch cams, arranged between the center of the movement and its periphery. The small dimensions of this cam system do not allow one to obtain satisfactory precision.